In recent years, with the increasing amount of data handled by users in information communication terminal apparatuses such as mobile telephones, a backup time and power consumption also tend to increase. Furthermore, CPU resources of a mobile telephone are also consumed during backup. In order to cope with these backup-related problems, there are proposals of various conventional methods for automatically carrying out backup during charging when a mobile telephone is not in use for a long time.
For example, Patent Document 1 discloses a method of automatically backing up data of a mobile telephone to a backup memory mounted in a battery charger upon detecting contact with the mobile telephone. However, according to the backup method disclosed in Patent Document 1, when approach or contact of the mobile telephone to/with the battery charger is detected, the backup data is automatically stored in the memory of the battery charger without access restriction, and therefore there is a danger that the backup data may be illegally accessed.
As a technique for solving this problem, a method is known where a user identification number (hereinafter referred to as “ID”) is read from an SIM (Subscriber Identity Module) of a mobile telephone and data is backed up in a backup memory mounted in a battery charger when an ID prestored in the battery charger matches the SIM ID (e.g., see Patent Document 2).    Patent Document 1: Japanese Patent Application Laid-Open No. 2001-285451    Patent Document 2: Japanese Patent Application Laid-Open No. 2003-188954